Patent GB-981777-A (GB)
Title: Improvements in or relating to punching machines
IPC: B21D28/04
Filed: 1964-04-07
Abstract: 981,777. Punching. HOUDAILLE INDUSTRIES Inc. April 7, 1961 [Nov. 1, 1960], No. 40290/64. Divided out of 981,775. Heading B3W. A structure for accurately positioning a workpiece in relation to a predetermined reference point includes a work support table, an elongated gauge bar assembly slidable on the upper surface of the table and having a reference surface for engagement by the workpiece and comprises a side rail bar structure secured to the table and slidably supporting a clamping device secured to one end of the gauge bar assembly and operative on a rack-like member secured to the table in a position adjacent to and parallel to the side rail bar structure, the device being arranged to hold or release the gauge bar assembly relative to the table. A punching machine including the positioning device comprises a C-shaped frame 31 having upper and lower arms 31a and 31b respectively. The lower arm 31b supports a sub-table 50 on which is mounted a work supporting table 33, and also supports a bed 38 on which the lower tool is mounted. A punch and stripper assembly 40 is supported by an upper tool support 41 which is held to the upper arm by clamps 42 and 43. The support 41 comprises arms 41a and 41b and between them is a reciprocating shaft 47 continuously driven by an eccentric 46 and selectively coupled to a ram 44 by an electrically operated clutch of the type described in Specification 890,250. Workpiece supporting table.-The table 33 is adjustable vertically by three screw jacks 58, which are operated simultaneously by a handwheel 63. Movement of the table in a horizontal plane is prevented by guide pins 64 passing through bushes 67 secured to the subtable 50. Removal of the workpiece can be assisted by lowering the table relative to the die. Gauging mechanism,-The work positioning mechanism comprises a rail 172, 173 at each side of the table 33, and includes a rack-like member 174 which is parallel to the rail 172 and is rotatably supported in end bearings. A block 176 slides on each rail and the blocks are connected by a gauge bar assembly 175 which is provided with a number of stops which are slidably adjustably supported thereon. The left-hand slide block 176 supports a device 177 for engaging the rack-like member 174, which in the embodiment described is threaded. A counter mechanism 178 is also mounted on this block. The device 177 comprises a pair of blocks 208, 209 which embrace the member 174 and which are controlled by a manually operated screw 212. The block 208 has thread teeth 208a formed therein which engage with the thread formed on the member 174. At one extreme position of the screw 212 both blocks are clear of the member 174 and the block can move freely along the member, at an intermediate position the threads 208a engage the member and the block 176 can be moved by rotating the member 174, and at a second extreme position of the screw, both blocks are clamped to the member 174 and prevent any movement. A primary method of indicating the fore and aft position of the gauge bar assembly comprises a counter 178 which is attached to the block 176 and is driven by gearwheels 226 and 228 from a gear-wheel 230 which engages the teeth of the member 174. For fine positioning of the gauging stops, the screw 212 is operated until the teeth 208a engage the thread teeth on the member 174 and the member is then rotated to move the slide block. There is a graduated thimble on the end of the member 174 to give an accurate indication of the position. Since the gauge bar assembly may be several feet in length a clamping means is provided near its mid-point, the means comprising an element 243, Fig. 8, secured to the gauge bar assembly and passing through an aperture in a guide block 248 secured to the table 33. A pin 246 slides in the guide block and is operated by a cam 245 formed on a shaft 244 to raise a friction pad 247 into clamping engagement with the element 243. The shaft 244 is operated by a handle 252.